Electrolytic cell or condenser.



E. E. F. GREIGHTONB ELECTROLYTIC CELL 0R CONDENSER. APPLICATION FILEDSEPT. 18, 1907.

923,774. Patented June 1, 1909;

Witnesses: Inventor:

W flmewhton x. 3% I by ELMER E. F. OREIGHTON, OF SOHENECTADY, NEW YORK,ASSIGNOR, BY MESNE ASSIGN- MENTS, TO GENERAL ELECTRIC COMPANY, ACORPORATION OF NEW YORK.

ELECTROLYTIC CELL OR GONZDENSEB.

Specification of Letters Fatent.

EPatented June 1, 1909.

original application filed July 9, 1906, Serial No. 825,195. Divided andthis application filed September 18, 1907. Serial No. 393,511.

To all whom it may concern:

Be it known that I, ELMER E. F. OREIGH- TON, a citizen of the UnitedStates, residing at Schenectady, county of Schenectady, State of NewYork, have invented certain new and useful Improvements in ElectrolyticCells or Condensers, of which the following is a specification.

My present ap lication is a division of an a plication filed y me July9, 1906, Serial 0. 325,195, lightning arrester, and relates particularlyto an electrolytic cell or condenser.

The novel features of my invention are particularly ointed out in the apended clalms, for a etter understanding 0' which reference may be had tothe following description taken in connection with the drawmg forming apart of this specification.

Figure 1 is a sectional elevation of an electrolytic condenser; Fig. 2is a perspective view of one of the conical cups forming a part thereof;and Fig. 3 is a perspective V16W of an insulator used for separating twoadjacent cups.

The electrolytic apparatus illustrated in Fig. 1 comprises a pluralityof c'onical aluminum dishes 1 nested one Within another and separated byporcelain or other insulators 2. These inulators are of cup sha e, asshown in I Fig. 8, and serve not only to e ectrically separate theplates but also serves to keep the dishes in position one above another.A conducting rod 3 connects with the lower plate and serves as a meansfor connecting the conductors to ground or to any suitable part of thedistribution system. A conducting rod 4 rests on and makes contact withthe u per dish or cup and is provided with a bindingpost 5 forconvenience in connecting the apparatus in circuit. A porcelaininsulator 6 separates and insulates rod l from the inclosing metal box 7within which the dishes are mounted. A suitable electrolyte isintroduced between each pair of dishes so that the column as a wholecomprises a series of, aluminum plates separated by electrol to. As anelectrolyte I use a solution of citric acid for l find that thissolution gives the apparatus a high capacity as a condenser and givesthe aluminum lates a high break-down resistance. The indlosing box maybe filled with oil or other insulating fluid of hi h thermalconductivity to prevent arcing a ong the edges of the aluminum dishesand to act as a cooling medium which absorbs heat from the plates andmaintains all parts of the device at substantially the sametemperature.The condenser action of the aluminum electrolytic condenser is usuallyattributed to the formation of a thin film of aluminum oxid or hydroxidon the aluminum late because of the oxidizing action of the e ectrolytewhen the aluminum plate is positive withrespect to the electrolyte. Thisfilm is of extreme thinness and seems to be. partially absorbed or eatenaway from the plate when the condenser is. inactive, though possibly itstill re mains and its apparent absence is due to the soaking u of theelectrolyte by the film. At any rate t e film does not appear to bepresent when current first flows between the plates but is developedafter the expenditure of considerable electrical energy and thereafterofiers a high resistance to the flow of current from the aluminum plate.With an electrolyte of citric acid the pressure between plates may be ashigh as 420 volts before the film breaks down and permits an appreciablecurrent to flow between the plates.

if an alternating ressure is applied to the terminals 3 and 5, t e appaatus operates as a true condenser and permits a certain quantitv ofcurrent to pass to and irom'the terminals, the current being to acertain extent dependent on the fre uency of the source.

Although the insu ating coating1 on the aluminum plates possesses a veryigh disruptive strength it is nevertheless of extreme thinness. As thecapacity of the condenser is to a certain extent dependent on thethinness of the dielectric, an aluminum condenser possesses markedadvantages over condensers of the ordinary type having a dielectric 0tmica or glass. Not only is the storage capacity of the aluminumcondenser veryhigh in proportion to its size and weight,-

found after the condenser has been in opera-' tion for some little time.This phenomenon is probably due to the formation of the oxid or hydroxidcoating by the oxidizing action of the leakage current, but whatever maybe the princi le underlying this phenomenon I find this 0 iaracteristicof the aluminum condenser of great value for certain special classes ofwork. When the condenser is first thrown in circuit its low resistance,or high leakage, permits a relatively large quantity of energy to passduring the first instant of operation, and then by oxidation, interposessufiicient resistance to prevent excessive current of normal voltagefrom flowing. The exact time interval which is necessary to allow thecondenser to rise from the condition of high leakage to that of lowleakage is diificult to determine, but in some instances, I have founditto be less than 1/260 of a second with plates which had previouslybeen subjected to the oxidizing action of current. Plates which have notthus been treated require a considerably longer time to build up totheir maximum insulating capacity, such a long time in fact, thatIconsider it desirable in constructing the apparatus shown in Fig. 1 tosubject the plates to a prolonged treatment with current to oxidize orotherwise form the plates.

I am aware that it has heretofore been proposed to form condenser platesby ma ing them anodes in an oxidizing solution and permitting directcurrent to pass for some time, but I find that such treatment is notaltogether satisfactor probably because of impurities in the aluminumwhich are not removed from the surface of the plate by the directcurrent and whichare present on the surface of the finished plate assmall specks or irregularities. I find that this diiiiculty can be larely overcome by forming the lates wit 1 alternating current instead ofirect current; possibly because of the scouring action which alternatingcurrent exerts on the surface of the aluminum late.

After the films have once been formed and the a paratus has beenassembled ready for use, t e electrolyte seems to act in some way on thefilm and weaken or break it down in pieces. This phenomenon may be dueto the corrosive action of the electrolyte; though possibly the acid isheld as a mechanical mixture in the film, or between the particles ofthe aluminum oxid and is decomposed or forced out by the first rush ofcurrent, thus restablishing the high resistance film. Thisrestablishment takes place so quickly that no detrimental quantity -oflinecurrent can discharge through the condenser.

The electrolytic condenser above described may be used for theprotection of electrical systems from lighting and other abnormalconditions, as described more in detail in my parent application. It isalso capable of various other a plications as will be apparent topersons ski led in the art.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,-

1. An electrolytic condenser comprising a plurality of oxidizable cupsseparated by an electrolyte containing citric acid.

2. An electrolytic condenser comprising a and plurality of aluminum cupsspaced apart contacting with a citric acid solution.

3. An electrolytic condenser comprising a plurality of watertightaluminum cups arranged one within another, an electrolyte between saidcups, and a body of insulating oil surrounding said cups.

4. An electrical condenser comprising a plurality of cup-shapedconductors arranged one Within another and se aratedby a conductivesolution, and an oi bath for insulating the edges of said cups.

5. In an electrol tic condenser, the combination of a plurality offrusto-conical aluminum electrodes, and insulating on s separating saidelectrodes and leaving a ree passage for the escape of gases.

6. In an electrolytic condenser, the combination of a plurality offrusto-conical aluminum cups arranged one above another,

insulating cups separatingsaid aluminum I cups, an electrolyte betweeneach pair oi aluminum cups, and a fluid insulator inclosing said cupsand electrolyte.

7. In an electrolytic condenser, the combination of a containingenvelop, a plurality of insulated plates therein, and means forsupporting said plates at their center only. 7 8. In an electrolyticcondenser, the combination of a containing envelop, a plurality offluid-containing plates nested therein, and insulating means forsupporting said plates at their centers out of contact with the walls ofsaid containers.

9. In an electrolytic condenser, the combination of a container, aplurality of insulated nested electrode plates therein and supportsextending from the walls of said container and engagingv with each ofthe end plates.

10. In an electrolytic condenser, an elec trolyte containing citricacid.

11. An electrolytic condenser comprisingathermal conductivity separatingsaid plates plurality of nested aluminum plates, an elecand electrolytesfrom the walls of said box. 13 trolyte between said plates, and a bodyof l 111 witness whereof, I have hereunto set oil insulating theiredges. F my hand this 16th day of September, 1907. 5 12. In an electrolticcondensel, the com- ELMER E. F. CREIGHTON bination of an inc osingbox, nested alu- Witnesses:

minum plates within said box, an electrolyte BENJAMIN B. HULL,

between adjacent plates, and a liquid of high MARGARET E. WOOLLEY.

